Shanghai-based petitioner Chen Jianfang has "disappeared" ahead of the ruling Chinese Communist Party's five-yearly national congress in Beijing on Thursday, as the authorities take action to prevent the country's army of petitioners from presenting grievances in the capital. Chen, who had planned to leave Shanghai to avoid detention amid a nationwide "stability maintenance" operation, was detained at the airport in the eastern city of Hangzhou, fellow activist Zhu Jindi told RFA. Her family had received a call from police from Hangtou township in Shanghai's Nanhui district, informing them of her detention, she said. "Her ex-husband doesn't know where she is right now," Zhu said. "The police called to tell him that Chen Jianfang was in Hangzhou airport, and telling him to call her up and get her to come home." "But after that, when he tried to call her, he couldn't get through to her cell phone." On the same day, authorities in the northeastern province of Liaoning forcibly wrested petitioner Jiang Jianjun's cell phone from her while she was in detention at a police station in the port city of Dalian, she told RFA. "Five or six of them were trying to snatch my phone off me in the police station," Jiang said. "My right arm was based against the chair a few times." "I think they want to take all of the evidence[I have collected] off my phone, so I smashed up my cell phone's memory card into little pieces," she said. "Now, nobody can get a look at it." A Hebei petitioner who declined to be named said police in the Beijing suburb of Fangshan have been placing out-of-town petitioners renting accommodation in the district under surveillance for the past few days. "They have been detaining large numbers of people in the biggest 'petitioner villages' in Beijing ever since[Oct. 4]," the petitioner said. "The local governments have called on the Beijing police to join in with the operation, and detain all the petitioners living in[the city]." "All of the petitioners with more sensitive cases have been placed under guard now, regardless of where we live," the petitioner said. "They will think of everything, do anything, make enquiries, to find out about your movements," he said. Metro passenger searches Police said they will begin searching people and their belongings on the Beijing metro on Tuesday, as security measures in the capital reach fever pitch. "All passengers have to get security checked," a passenger surnamed Liang told RFA. "They don't care if it makes you late for work, or if you have a serious illness, or some kind of emergency." "There are security scanners at all stations on the metro right now, and the entire commuting population has to form a line to go through them," she said. "They are making everyone late." Major political events like the five-yearly congress of the Chinese Communist Party are a big draw for those hoping their grievances will get a hearing, or at least some publicity. But many petitioners said they are being threatened and detained by local officials before they have even left their homes. Authorities have now perfected a system of "interceptors," local enforcement officers sent by local governments to ensure no tales are told of their misdeeds in Beijing. Petitioners are often held in unofficial "black jails," and face other forms of threats, harassment, and extrajudicial detention. Beijing rights activist Xie Xiaoling said she is currently under surveillance at her Beijing home. "The ... police our outside my door," she said. "They eat and sleep there, watching me 24 hours a day." "If I go out, then I will have police officers following me, so I have totally lost my freedom," she said. In the central province of Hubei, Xu Qin, of the China Rights Observer website, said she is also under guard for the duration of the party congress, which President Xi Jinping has announced will have the theme "the Four Greats." "There are at least a dozen of them," Xu said. "They said they couldn't take me at my word so I had better cooperate." "They said they'd sleep on mattresses on the floor, although it would be better if I had a room for them," Xu said. "They wanted to sleep in my living room but I put my foot down, because it would disturb my family." "I wouldn't let them inside my apartment," she said.